1. Field
Aspects of the present innovations relate to origin/location estimation, and, more particularly, to systems and methods associated with processing origin/location information of a source or event.
2. Description of Related Information
Methods of determining the location of a signal source based on the arrival time measurement and/or arrival angle measurements of signals sent by or reflected off of the source object have numerous technological uses. Examples include the computation of the epicenter of an earthquake from the arrival time of the ground motion received at a set of seismometers; location of a mobile wireless telephone handset by measurement of the arrival time and arrival angle of RF signals received by a set of wireless telephone base stations (known as “E-911”); location of an aircraft via measurement of the arrival time of RF radiation reflected off of the aircraft a received by a radar receiver; and acoustic location of a weapon discharge event by measurement of the arrival time muzzle blast sound at a set of acoustic sensors.
Numerous existing techniques of source localization cover various aspects of the time difference of arrival location problem, including methods for determining the time differences of arrival accurately via cross-correlation or super-resolution techniques. Once time difference of arrivals have been computed, numerous methods can be used to compute the source location. For example, existing techniques in this vein include computations based on constant-spaced receivers and chi-square minimization methods.
Some techniques concern mixing various signal types in the source location problem, such as the combination of GPS and mobile telephone handset signals.
Still other techniques focus on the source location from the time differences of arrival and/or angle of arrivals. This process is often called “triangulation” but typically involves intersection of hyperboloids defined by the relative arrival time difference between pairs of receivers at known positions. Triangulation methods include numerical solution to intersecting hyperbolas and cost-function minimization over three base stations.
In short, prior methods in the field of source localization either constrain the source in two-dimensions by solving the entire problem in two dimensions, thus neglecting the effects of the third dimension on the source-receiver travel time, or they localize the source in three dimensions, which makes correct use of the source-receiver distance but which can generate unsuitable results, such as when unavoidable errors are introduced in measurement of the time of arrival of a signal, or in the positions of the receivers, or in the knowledge of the propagation velocity in the signal medium. One or more aspects consistent with the innovations herein may overcome existing drawbacks or limitations, such as above, via methods involving improved location estimation processing features, which may include constraining source locations to an arbitrary plane, such as a local approximation of the surface of the Earth.